Mitochondria-rich, proton-secreting epithelial cells

Area of Science:

• Cell Biology
• Physiology
• Biochemistry

Background:

• Specialized proton or bicarbonate secreting cells, known as mitochondria-rich (MR) cells, are found in various vertebrate and invertebrate transporting epithelia.
• These MR cells exhibit high expression of vacuolar-type proton-pumping ATPase (H+V-ATPase), localized on intracellular vesicles and the plasma membrane.

Purpose of the Study:

• To review the structural and functional characteristics of proton-secreting cells.
• To describe the tissue distribution of these specialized cells.
• To discuss the known functions of MR cells in different physiological contexts.

Main Methods:

• Literature review focusing on studies of mitochondria-rich cells and H+V-ATPase.
• Analysis of structural and functional data from various species.
• Synthesis of information on tissue distribution and physiological roles.

Main Results:

• Proton secretion in MR cells is physiologically modulated by recycling H+V-ATPase via nonclathrin-coated vesicles.
• MR cells are involved in kidney's urinary acidification, epididymis/vas deferens' sperm development, osteoclast bone remodeling, and insect midgut K+ secretion.
• H+V-ATPase is a key component in the function of these diverse proton-secreting cells.

Conclusions:

• Mitochondria-rich cells are critical for diverse physiological functions across species through regulated H+V-ATPase activity.
• Understanding the structure, distribution, and function of these cells provides insight into epithelial transport and cellular energetics.
• The H+V-ATPase plays a central role in proton secretion and related physiological processes in both epithelial and non-epithelial cells.